Cat Growth?

I've got a two month old kitten who just doesn't seem to be growing. His 7 1/2 month old big brother, Mozart, grew SO MUCH. He's still growing, in fact, and has gotten absolutely ENORMOUS.

I'm not really worried about the little guy (Noodles) Since he's healthy and energetic. I'm just wondering about the usual grow cycle of a cat. He's so small, and I worry if he's growing right. He gets Purina One kitten food, and eats like a little pig.

He's obviously not going to be a big cat like Mozart, but I do wonder about him sometimes.

Cats, like most animals/people are all different sizes. Out of my nine, I have 5 larger cats and 4 smaller cats. :)